It would be extremely useful for someone to explain it. I have read that for chelates you do get a stability constant, and if you google a specific chelate you do find it quite easily. So from my understanding that shows how strong the Nutrient-chelate complex is. From a bit of field experience it does seem to me like EDTA is a stronger chelation agent than amino acids. So if I’m doing tank mixtures I prefer to go with EDTA.

I have also heard that applying large doses of EDTA as a foliar could be toxic. Therefore if I’m trying to correct a deficiency I’d rather do one of the other chelation agents.

As far as for the most efficient absorption, I find it really hard to gather good information. I’ve also heard some really good things about citric acid. Specifically Potassium-Citrate complexes.

But it does seem like information regarding the absorption of chelating agents is quite scarce.